Record second-factor service delivery PR (#40)

docs/implementation.md

@@ -580,3 +580,6 @@ Existing settings screens still use preview adapters; SMS/push/TOTP/passkeys,
 factor removal/recovery, payout integration and a separate process are not
 implemented. Successful-commit response loss still requires login restart;
 notification queue acceptance is not inbox delivery.
+
+Delivered in [PR #41](https://git.sendico.io/tech/sxchnge/pulls/41) against `main`.
+Branch `twofactor-40` is pushed. The PR is left open for review; no merge was performed.